Anomalous tension–compression asymmetry in amorphous silicon: insights from atomistic simulations and elastoplastic constitutive modeling,Journal of the Mechanics and Physics of Solids

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Anomalous tension–compression asymmetry in amorphous silicon: insights from atomistic simulations and elastoplastic constitutive modeling
Journal of the Mechanics and Physics of Solids ( IF 5.3 ) Pub Date : 2024-02-13 , DOI: 10.1016/j.jmps.2024.105575
Bin Ding , Liang Hu , Yuan Gao , Yuli Chen , Xiaoyan Li

Recent experiments observed an inherent, anomalous tension-compression (T-C) asymmetry with T>C in microscale amorphous silicon (a-Si), which is free of dominant microcracks or dislocations. However, quantifying the disordered structure of a-Si and correlating it with T-C asymmetry remains mysterious. Here, we first conduct a series of atomistic simulations to explore this anomaly in a-Si. Results reveal a positive correlation between cooling rate and fraction of liquid-like phase , suggesting that higher cooling rates trap more atoms in liquid-like phase. Uniaxial tension and compression tests reveal that T-C asymmetry with T>C persists across all cooling rates, where the physical origin is attributed to variations in initial and its subsequent spatial and temporal evolutions during loading. A physics based, Mohr-Coloumb type elastoplastic constitutive model, determining cohesion by the content of liquid-like component , successfully reproduces the observed anomalous T-C asymmetry and its dependence on the initial structure in a-Si. Furthermore, the degree of asymmetry tends to diminish with an increase in initial , a trend general to both amorphous Si and CuZr metallic glass (MG). While the contrasting atomic volumes of the liquid-like phase in a-Si and MG explain their differing T-C asymmetries, with a-Si exhibiting T>C and CuZr exhibiting T

中文翻译：

非晶硅中的反常拉压不对称性：来自原子模拟和弹塑性本构建模的见解

最近的实验观察到微尺度非晶硅 (a-Si) 存在固有的反常拉压 (TC) 不对称性，T>C，且不存在显着的微裂纹或位错。然而，量化非晶硅的无序结构并将其与 TC 不对称性关联起来仍然是个谜。在这里，我们首先进行一系列原子模拟来探索非晶硅中的这种异常现象。结果显示冷却速率与类液相分数之间呈正相关，这表明较高的冷却速率在类液相中捕获更多原子。单轴拉伸和压缩测试表明，TC 不对称性（T>C）在所有冷却速率下都持续存在，其物理起源归因于加载过程中初始及其随后的空间和时间演变的变化。基于物理学的莫尔-库伦型弹塑性本构模型，通过类液体成分的含量确定内聚力，成功地再现了观察到的异常 TC 不对称性及其对非晶硅初始结构的依赖性。此外，不对称程度往往随着初始的增加而减小，这是非晶硅和 CuZr 金属玻璃 (MG) 的普遍趋势。虽然 a-Si 和 MG 中类液相的对比原子体积解释了它们不同的 TC 不对称性，其中 a-Si 表现出 T>C，而 CuZr 表现出 T

更新日期：2024-02-13

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